#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>
#include <time.h>

#define Size 10

//初始化函数
void InitBoard(char (*Board)[Size])
{
    for(int i = 0; i < Size; i++)
    {
        for(int j = 0; j < Size; j++)
        {
            Board[i][j]  = '-';
        }
    }
}

//打印棋盘
void PrintBoard(char (*Board)[Size])
{
    printf("    ");
    for(int i = 0; i < Size; i++)
    {
        printf("%4d", i+1);
    }
    printf("\n");
    for(int i = 0; i < Size; i++)
    {
        printf("%4d", i+1);
        for(int j = 0; j < Size; j++)
        {
            printf("%4c", Board[i][j]);
        }
        printf("\n");
    }
}

//下棋
bool MakeMove(char (*Board)[Size], int row, int column, char player)
{
    //非法位置
    if(row < 0 || row >= Size || column < 0 || column >= Size)
    {
        printf("非法的下棋位置！请重新输入！\n");
        return false;
    }
    //该位置已经有棋子了
    if(Board[row][column] != '-')
    {
        printf("该位置已经有棋子了，请重新输入！\n");
        return false;
    }
    Board[row][column] = player;
    return true;
}

//判断位置是否合法
bool IsValidPlace(int row, int column)
{
    if(row < 0 || row >= Size || column >= Size)
        return false;
    return true;
}

//判胜
bool CheckIsWin(char (*Board)[Size], int row, int column, char player)
{
    //4个方向上的向量
    int direction[4][2] = 
    {
        {1, 0},
        {1, 1},
        {0, 1},
        {-1, 1}
    };

    //遍历4个方向，数棋子数量
    for(int i = 0; i < 4; i++)
    {
        int count = 1;
        //下一颗棋子的位置
        int dx = row + direction[i][0];
        int dy = column + direction[i][1];
        while(IsValidPlace(dx, dy) && Board[dx][dy] == player)
        {
            count++;
            if(count >= 5)
                return true;
            dx = dx + direction[i][0];
            dy = dy + direction[i][1];
        }

        //反方向继续找
        dx = row - direction[i][0];
        dy = column - direction[i][1]; 
        while(IsValidPlace(dx, dy) && Board[dx][dy] == player)
        {
            count++;
            if(count >= 5)
                return true;
            dx = dx - direction[i][0];
            dy = dy - direction[i][1];
        }
    }
    return false;
}

//判平
bool CheckIsDraw(char (*Board)[Size])
{
    for(int i = 0; i < Size; i++)
    {
        for(int j = 0; j < Size; j++)
        {
            if(Board[i][j] == '-')
                return false;
        }
    }
    return true;
}

bool AIMakeMove(char (*Board)[Size], char player, char ai, int PlayerRow, int PlayerColumn)
{
    //优先取胜策略
    for(int i = 0; i < Size; i++)
    {
        for(int j = 0; j < Size; j++)
        {
            if(Board[i][j] == '-')
            {
                Board[i][j] = ai;
                if(CheckIsWin(Board, i, j, ai) == true)
                {
                    return true;
                }
                Board[i][j] = '-';
            }
        }
    }

    /* ... to do */
    //阻止对手策略  
    for(int i = 0; i < Size; i++)
    {
        for(int j = 0; j < Size; j++)
        {
            if(Board[i][j] == '-')
            {
                Board[i][j] = player;
                if(CheckIsWin(Board, i, j, player) == true)
                {
                    Board[i][j] = ai;
                    return true;
                }
                Board[i][j] = '-';
            }
        }
    }

    //下在玩家周围策略
    int direction[8][2] = 
    {
        {1, 0},
        {-1, 0},
        {0, 1},
        {0, -1},
        {1, 1},
        {1, -1},
        {-1, 1},
        {-1, -1}
    };

    while(1)
    {
        //随机数的产生由随机种子决定
        //随机种子不变，随机数就不会变
        //以当前时间作为随机种子
        srand(time(NULL));
        int i = rand() % 8;

        int dx = PlayerRow + direction[i][0];
        int dy = PlayerColumn + direction[i][1];
        if(IsValidPlace(dx, dy) && Board[dx][dy] == '-')
        {
            Board[dx][dy] = ai;
            return true;
        }
    }
    return false;
}

int main()
{
    char Board[Size][Size] = {0};
    InitBoard(Board);
    
    char player = 'X';
    int row = 0, column = 0;
    while(1)
    {
        PrintBoard(Board);
        
        printf("请|%c|选手下棋：", player);
        //玩家下棋
        if(player == 'X')
        {
            scanf("%d %d", &row, &column);
            if(MakeMove(Board, row-1, column-1, player) == false)
                continue;
        }
        //电脑下棋
        else
        {
            printf("AI正在下棋......\n");
            if(AIMakeMove(Board, 'X', 'O', row - 1, column-1) == false)
                continue;   
        }

        if(CheckIsWin(Board, row-1, column-1, player) == true)
        {
            PrintBoard(Board);
            printf("恭喜|%c|选手获胜！\n", player);
            break;
        }

        if(CheckIsDraw(Board) == true)
        {
            PrintBoard(Board);
            printf("平局！\n");
            break;
        }
        player = (player == 'X' ? 'O' : 'X');
    }
    return 0;
}